2.0 Analysis 2.1 Introduction There were no witnesses to the occurrence and no survivor; the immediate circumstances leading up to the accident are unknown. The reported wind direction, the aircraft heading, the position of the flaps at impact, and the location of the accident site are consistent with the accident having occurred during an approach for landing. It is, therefore, probable that the pilot had completed a take-off from the lake, and that he was attempting to return to the lake, for undetermined reasons, when the accident occurred. The wreckage trail and damage patterns were consistent with the aircraft having stalled at a low altitude, which precluded an effective recovery. The conditions that would most likely have contributed to the loss of control are gusty winds, degraded flight performance due to the aircraft's high gross weight, disruption of airflow and drag because of the external load, and a possible reduction in available engine power due to a faulty magneto p-lead. 2.2 Weight and Balance The aircraft weight at the time of the accident exceeded the maximum allowable take-off weight by at least 162pounds. Combined with the effects of the moose antlers being carried externally, this would have reduced the aircraft's flight performance, adversely affected the stability and slow flight characteristics, and increased the stall speed. The lack of a stall warning system may have delayed the pilot's recognition of the approaching stall. There were significant errors in the amended weight and balance reports that were available to the pilot. While there was no indication that the weight and balance report errors contributed directly to the accident, the errors would have precluded an accurate calculation of the actual weight and centre of gravity location. The Piper PA-18 weight and balance reports and the PA-18 type certificate identify different datums for weight and balance purposes. Because of this conflict, there is a potential for the inadvertent and concurrent application of two different datums in individual weight and balance amendments. While centre of gravity does not appear to be a factor in this accident, the circumstance of having two datums for the weight and balance reference material increases the likelihood that errors will occur during weight and balance amendments. This, in turn, increases the potential for the aircraft to be loaded outside of the centre of gravity limits. Improper loading could contribute to loss of control, serious injury, and fatality in other occurrences. 2.3 External Loads Carriage of external loads, such as moose antlers, is considered an acceptable practice by outfitters and other float plane operators. The risks associated with the carriage of external loads require that consideration be given to the performance degradation. While the exemption to carry external loads with passengers did not apply to this flight, since no passenger was being carried, voluntary compliance with the conditions required for the exemption to CAR703.25 would have reduced the risks associated with the flight. CAR 703.25 could be misinterpreted as allowing the carriage of external loads without conditions when passengers are not carried, even though the flight authority for an aircraft becomes invalid if an aircraft has not been certified to carry an external load. 2.4 Company Organization and Management There were several unsafe conditions associated with the operation of the aircraft that increased the risk on this flight. The Company Operations Manual contained conflicting information and no specific guidelines concerning operations with external loads, and the PiperPA-18-150 was not approved for the carriage of external loads under the aircraft Type Certificate. However, an external load was being carried. There was no evidence that a proving flight had been accomplished to determine the flight characteristics associated with the external carriage of moose antlers. The empty weight of the aircraft was under-represented in the available weight and balance reports, and the aircraft's gross weight was considerably above the maximum allowable take-off weight at the time of the accident. The cabin load had not been secured prior to flight, despite the anticipation of turbulent flight conditions. The right magneto p-lead had been in poor condition for some time, and the discrepancy had not been detected during recent maintenance or operation of the aircraft. The organizational structure of the company placed all of the administrative and risk management responsibilities in the hands of one individual. This negated the advantages of management checks and balances within the company, which normally provide a level of independent oversight, especially in the area of quality assurance. This may have compromised the level of safety within the company. 2.5 Transport Canada Overview The aviation system in Canada relies on built-in checks and balances such as multiple-person management structures within commercial operations and regulatory audits to ensure optimal safety. Despite company risk indicators that included a recent change of ownership, a history of accidents and incidents, and a management structure that placed all operational and maintenance supervisory responsibilities in the hands of one individual, the company had not been audited by CBA inspectors since prior to the issue of the original AOC in1990. It is possible that a Transport Canada audit would have revealed many or all of the unsafe conditions that were identified during this investigation. 2.6 Right Magneto P-Lead The right magneto p-lead had been in poor condition for some time prior to the accident. The degraded condition of the p-lead had not been detected during recent maintenance, and may have resulted in a partial loss of power immediately prior to the accident. 3.0 Conclusions 3.1 Findings as to Causes and Contributing Factors The aircraft stalled at low altitude, which precluded an effective recovery; the aircraft was not fitted with a stall warning system, which may have delayed the pilot's recognition of the impending stall. The combination of the aircraft being at least 162pounds above the maximum seaplane weight of 1760pounds and the moose antlers being carried externally degraded the performance of the aircraft. 3.2 Findings as to Risk The PA-18 Type Certificate does not permit the carriage of external loads; there was no evidence that a proving flight had been accomplished to determine the flight characteristics associated with the external carriage of moose antlers; and the Company Operations Manual did not provide direction to flight crews concerning operations with external loads - all of which increased the risk associated with the flight. Several weight and balance report amendments for the aircraft contained aircraft empty weight and centre of gravity errors, which precluded an accurate weight and balance calculation and increased the risk that the aircraft could be flown outside of weight and balance limits. Canadian Aviation Regulation703.25 could be misinterpreted to allow the carriage of external loads without conditions when passengers are not carried, even though the flight authority for an aircraft becomes invalid if an aircraft has not been certified to carry an external load. The company had not undergone a Transport Canada Commercial and Business Aviation operational audit since prior to the issue of the Air Operator Certificate in1990, which precluded the early identification of several latent safety deficiencies within the company. 3.3 Other Findings The right magneto p-lead was defective, which may have resulted in a partial loss of engine power. For some time prior to the accident, the rear control stick socket was contacting the aft wall of the protective cover when the control stick was in the full-aft position. The Borer propeller installation, under Supplemental Type Certificate SA279AL, was not approved for operation in combination with Canadian Aircraft Products67-2000floats. There was no record of the ski cargo box having been installed in the aircraft. 4.0 Safety Action 4.1 Action Taken On 28 January 2004, the TSB issued an Aviation Safety Information Letter (A040002, PA-18 Weight and Balance Information) to The New Piper Aircraft, Inc., with a copy to Transport Canada. The letter concerned the conflict between datum information on the original PiperPA-18 aircraft weight and balance documents and that on the current type certificate. The information was provided for whatever follow-up action the company deemed appropriate. On 15 April 2004, the TSB sent to Transport Canada an Aviation Safety Advisory regarding company audits (A040022, Transport Canada Regulatory Overview).